1. Field of the Invention
This invention relates to a composite material and a method for the manufacture of that composite material. The composite material has discrete liquid phase sintered tungsten heavy alloy shapes embedded in a solid state sintered matrix. Both the liquid phase sintering of the embedded shapes and the solid state sintering of the matrix are performed at the same temperature using a single co-sintering process. The co-sintering process allows for uniform sintering shrinkage of the embedded shapes and the surrounding matrix and thereby avoids the formation of defects such as pores and cracking that can occur by conventional processes. In one embodiment, the composite is formed into a component for a fragmentation device having sufficient strength and generating sufficient momentum to penetrate fortified defenses prior to detonation. On detonation, the component releases discrete, high density fragments.
2. Description of the Related Art
The military has a need for devices that can be deployed from a safe distance and distribute a lethal cloud of fast-moving fragments on detonation. Such devices presently use an embossed steel shell that breaks apart along a pattern of thin sections on detonation. Due to the relatively low density of steel, this configuration is not effective for penetrating defensive fortifications, such as concrete or steel lined bunkers, prior to detonation.
Momentum is a function of (mass)×(velocity). Accordingly, shaped charge liners and fragmentation devices are frequently formed from a tungsten-base alloy. Commonly owned U.S. Pat. No. 7,360,488 titled “Single Phase Tungsten Alloy for Shaped Charge Liner,” issued Apr. 22, 2008, discloses a cast metal alloy for forming a shaped charge liner, fragmentation warhead, warhead casing and the like that is an alloy of cobalt, tungsten and nickel. U.S. Pat. No. 6,960,319 titled “Tungsten Alloys for Penetrator Application and Method of Making Same” discloses a kinetic energy penetrator formed from an alloy of tungsten, one or more elements selected from the group consisting of nickel, iron, chromium and cobalt and one or more elements selected from the group consisting of titanium and aluminum. The kinetic energy penetrator is formed by blending a mixture of the powdered elemental components or alloys and then consolidating by solid state sintering. U.S. Pat. No. 6,827,756 titled “Tungsten Heavy Alloy for Penetrating Splinter Shell and Forming Method Thereof” discloses a tungsten-molybdenum-nickel-iron shell formed by compacting elemental or alloy powders of the desired composition to form a green blank and then liquid phase sintering to consolidate. All three of U.S. Pat. Nos. 7,360,488, 6,960,319 and 6,827,756 are incorporated by reference in their entireties herein.
There remains, therefore, a need for a high density, high strength, component for a fragmentation device that does not have the limitations of the prior art.